Try to prevent the cd from spinning up. I did this on a MacBook with slot-loading mechanism. Carefully insert one end of something thin, flat plastic (credit card...) and try to push it down on top of the cd to stop it from spinning if possible. Hold it there until the cd ejects.
This made my cd in the laptop eject.
I don't know if it works the same on the car. Haven't tried. Let us know if you try.